The seeds for the 2016 US Open are based on the WTA rankings as of 22 August 2016. The 2016 US Open Qualifying Tournament takes place from Tuesday, Aug. 23, through Friday, Aug. 26.
The 2016 US Open runs from Monday, Aug. 29, through Sunday, Sept. 11. Schedule | 2016 US Open Official Site - A USTA Event

Perhaps Vika will be there next year...or in the 2018 Australian Open......

The seeds for the 2016 Wimbledon Championships are based on the WTA rankings as of 20 June 2016. The draw for the tournament will be held on Friday, June 24 2016.
Main draw matches will start on Monday, June 27 2016.http://www.wimbledon.com/index.html

To date, Vika Azarenka has won twenty WTA singles titles including two grand slam singles titles, six WTA Premier Mandatory singles titles and three WTA Premier 5 singles titles.
She was also the runner-up at the 2011 WTA Tour Championships, 2012 US Open and 2013 US Open.